Cracked head (bike that is) symptoms ?.

[Dick Scratcher]

CB250RSA, the normal (!) crack in the cylinder head. It would appear that it's not unusual on these and almost obligatory on XBR500's and all I get told is "Ignore it, they're all like that". On the assumption that they indeed are 'all like that' what symptoms are there or could there be......does the motor bang on regardless ?......does it die when it gets hot ?......is there a distinct power (such as it is) drop off ?.......should I be concerned. What does the brains trust have to say ?.

[SteveC#222]

Just ignore it!...

....seriously. a lot of XBR's have it and most owners don't even know unless they take the head off. Most of the time on standard bikes it makes no difference and gives no symtoms as there isn't really a problem. If fact worring about it can make it worse - I was talking to a guy at Stafford some years ago who had found the crack and went to great expence to get it alloy welded and skimmmed and the bike never ran properly again!

Maybe worry if you're planning to race it or tune it but otherwise ignore it.

[Dick Scratcher]

Thanks Steve#222 that's the answer that I was hoping to read so I'll bash on regardless............unless of course anyone else on 'The Panel' comes up with another opinion (or proof) that's contrary. If another forum member chooses to put his 'two-pennorth' in I'll be pleased to read it !..................Dick S.

[tevie54]

I'm assuming you mean the crack between the spark plug hole and a valve seat? Some have them, some don't. It doesn't go that deep and when the engine's hot it closes up so i wouldn't worry too much.

[Dick Scratcher]

Thanks tevie54, yes you've got it, that's the crack...........I'll keep on riding until summat 'appens.

[Propellor]

Do these engines use a "skull cap"?

[Dick Scratcher]

In the case of the 250RS Propeller no they didn't, just valve seats and a 'plug-hole' crammed into a small combustion chamber leaving not a lot of 'meat' in the way of surroundings.